a. Field of the Invention
The present invention relates to the class of surgical instruments and processes.
More particularly, it relates to instruments used in the dilation of the Sphincter of Oddi often done in treatment of common bile duct pathological conditions such as stones and stricture.
More particularly, it relates to an improved catheter and dilator device for dilation of the Sphincter without the risk of excessive and life threatening trauma in present devices.
On many occasions, the common duct is opened to search for and remove stones. Certain indications for exploration of the common duct have been devised and whenever one or more of these indications are present, the duct is most often explored. Some of the common indications are: when a stone is palpable in the common duct; when the common duct is dilated; when there are small stones present in the gallbladder; when jaundice of the obstructive variety is present and various others. After the common duct has been opened and explored for stones, it is necessary to dilate the Sphincter of Oddi. This is done to encourage and facilitate passage of residual stones or debris left in the common duct. The Sphincter is also dilated to make sure that there is no stricture of the Sphincter of Oddi or stone present in the ampulla.
The usual procedure in this type of operation has been to make a longitudinal incision in the anterior surface of the common duct just distal to the entrance of the cystic duct for the entrance of the probe. The usual probe used for this purpose comprised a malleable metal rod approximately fifteen inches in length and having a portion approximately twice the length of the probe portion and an enlarged portion at the end of the probe portion. The probe is passed through the incision with the probe shaped to fit the curve of the common duct and its enlarge tip forced through the Sphincter of Oddi into the duodenum, thereby dilating the Sphincter of Oddi. To increase the dilation it has been customary to provide a plurality of probes, each having an increasingly larger tip, and successively inserting and removing the various probes.
The preceding steps not only increase the time of the probing operation due to the fact that each probe must be separately shaped to fit the curve of the common duct, but the insertion of the various probes increases the danger of tearing the common duct or pushing a hole in a portion of the common duct in an area not visible to the operator.
b. The Prior Art
An improvement to the above procedure and devices has been discussed by Maurice Miller in U.S. Pat. No. 3,196,876 issued July 27, 1965.
Miller discloses a one piece probe with a malleable lead portion and an enlarged oval tip which is manipulated through the Sphincter of Oddi. Then a number of incrasingly larger sleeves are threaded there over to enlarge and dilate the Sphincter. There are grave disadvantages to the system of Miller.
Firstly, it is time consuming and traumatice to bend stiff metallic dilators and identifying the proper location of the tip by outside manipulation.
Furthermore, the sharp rigid metallic tip of Miller's probe poses a high risk of creating peroration and false passage to the blinded portion of the distal common duct and also to the pancreas, leading to serious life threatening complications from digestive pancreatic enzymes.
Miller's probe tip is small and sharp as compared to Bake's dilator (1937 model) which is very popular among surgeons presently. It (Miller's) poses an unsureness of the passage of the Sphincter by palpation from outside of the duodenum. It is very difficult to identify whether it passed through the Sphincter opening or just invaginated (tenting). The unsure and potentially wrong location of Miller's probe followed by a series of Miller's malleable sleeve dilators can lead to the bursting of the blinded area of the distal common duct wall and may also lead to serious damage to the head of the pancreas.
Also, Miller's graduated dilator is made of a metallic malleable encircled type metal as illustrated and is not as flexible as compared with plastic material to follow the curved contour of the common duct. It also has the disadvantage of having to be manually bent to adjust to the contour of the common duct prior to introduction.
Lastly, Miller's sleeve dilator does not have a handle to grip for control and transmission of force to the dilator tip; and the small openings of the metallic dilators make cleaning and sterilizing difficult leading to unsureness of sterilization.
Another dilating apparatus previously discussed is that of Leland C. Gravlee in U.S. Pat. No. 3,811,449 issued May 21, 1974.
Gravlee discloses an apparatus which comprises an elongated flexible probe of uniform diameter and a dilator which slides thereover with further increasing diamter dilators sliding thereof.
A similar method has been used to dilate the Sphincter of the esophagus anus and cervical canal.
Since Gravlee's probe is less than three millimeteres in diameter, it is impossible for the surgeon to determine the proper location of the tip by outside palpitation. This can result in the tip being in the wrong location causing damage to the duct wall. Secondary damage to the pancreas might also occur.
Also, the primary probe might easily lead to invagination of the Sphincter of Oddi (tenting) into the duodenum instead of passing through the Sphincter opening and may lead to dilation of the wrong area.
Gravlee mentions an advantage of medical instrumentation through his dilator. There is no reason to insert such an instrumentation through the curved common duct. It is impossible to see the distal part of the common duct through such a small caliber of any opening of a dilator to perform a surgical procedure. There are much better and safer procedures to perform removal of a stone and biopsy. Sphincters should not be dilated more than six mm in diameter, (many doctors state that higher dilation will result in more stricture formation in the future except for unusually large dialted common ducts). It is practically impossible to perform biopsies or remove stones using Gravlee's instrument due to the curvature of the common duct and the small lumen.